1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a flat and light LCD device.
2. Description of the Related Art
In general, a LCD device includes a LCD panel for displaying an image, and a driving unit for driving the LCD panel. The LCD panel is fabricated by attaching a thin film transistor array substrate to a color filter substrate with a cell-gap therebetween, and filling the cell-gap with a liquid crystal material to form a liquid crystal layer. The driving unit includes a gate driving unit, a data driving unit and a printed circuit board (PCB). The gate driving unit includes a plurality of driving integrated circuits (D-IC), and supplies a scan signal to the gate lines sequentially to activate the pixels. The data driving unit also includes a plurality of D-ICs, and supplies an image signal to the pixels through the data lines.
The printed circuit board (PCB) supplies control signals and an image signal to the gate driving unit and the data driving unit. Various devices are mounted on the PCB. The PCB processes and converts externally supplied data into control signals for driving a LCD device. Then, the PCB distributes the control signals to the gate driving unit and the data driving unit.
Several methods can be used for electrically connecting the D-ICs constituting the data driving unit and the gate driving unit to the LCD panel, examples of which are tape-automated bonding (TAB) method and chip-on-glass (COG) method. In the TAB method, the D-ICs are connected to the LCD panel by electrically connecting a TCP (tape carrier package) at the location where the D-ICs are mounted to the LCD panel. An edge of the thin film transistor array substrate is exposed when the two substrates are attached because an area of the thin film transistor array substrate is larger than that of the color filter substrate. Moreover, the TCP is attached to the exposed area along the edge. One D-IC is mounted on each TCP.
In the COG method for electrically connecting the D-ICs to the LCD panel, the D-ICs are directly mounted on the LCD panel. The COG method has several advantages. For example, in the COG method, the LCD panel can be made compact because the D-ICs are directly mounted on a glass substrate of the LCD panel. However, the COG method may cause damages to the glass substrate due to the high temperature required for directly mounting the D-ICs on the glass substrate. For this reason, the TAB method, which involves simpler processes, is mainly used.
FIG. 1A is a view of a related art LCD device employing a TAB method. As shown in FIG. 1A, the LCD device includes a thin film transistor array substrate G1 and a color filter substrate G2 which are attached to each other. A plurality of TCPs 10 are electrically connected to the thin film transistor array substrate G1. A D-IC 9 is mounted on each TCP 10. A PCB 5 is connected to the TCP 10 to provide an image signal and a control signal to the thin film transistor array substrate G1 through the TCP 10. One side of the TCP 10 is connected to an edge of the thin film transistor array substrate G1. Another side of the TCP 10 is connected to the PCB 5.
Although not shown in FIG. 1A, gate lines and data lines are arranged horizontally and vertically on an LCD panel. The gate lines and the data lines are attached to the thin film transistor array substrate G1 and the color filter substrate G2, and cross each other. The crossing of the gate lines and the data lines define pixel regions in a matrix arrangement. The pixel is a minimum unit for displaying an image. The arrangement of the pixels form an active area 13 where an image is actually displayed.
FIG. 1B is an enlarged view of a portion ‘A’ of the related art LCD device depicted in FIG. 1A. As shown in FIG. 1B, a width (WT) of the TCP 10 attached to the LCD panel is smaller than a width (WL) of a region within the active area 13 where data/gate lines 20 for connection to the TCP 10 are formed. A plurality of link lines 22 are formed at the LCD panel. The plurality of link lines 22 are connected to data/gate lines 20. Because the intervals between link lines 22 are narrower than the intervals between the data/gate lines 20, the link lines 22 are spread out, like the ribs of a fan, from the TCP 10 to the active region 13 for connection to the data/gate lines 20.
FIG. 1C is an enlarged view of a portion ‘B’ of the related art LCD device depicted in FIG. 1B, showing a connection between a TCP output line and a link line. As shown in FIG. 1C, a link line 22 connected to a TCP output line 21 is bent at an angle for connection to the data and gate lines. The point at which a link line is bent is defined as a link bending point 25. The link lines 22 and the TCP output lines 21 are disposed at regular intervals.
To prevent the link lines 22 from short-circuiting each other, link bending points 25 are obliquely arranged between each side of the TCP 10, and a central region thereof. Accordingly, a distance of the link bending points 25 from the TCP 10 increases as the link bending points get closer to the central region of the TCP 10. Moreover, as the link bending points get closer to the central region of the TCP 10, each corresponding link line 22 is extended from one side of the TCP 10 by an extension length (LP). Thus, the link bending points 25 are formed outside, not within the TCP 10 region.
The extension of the link lines 22 allows an interval to be maintained between the link lines 22 to prevent the link lines from short-circuiting each other. Such a short-circuit could generate an interference between the link lines 22. An area in which link lines 22 are formed is referred to as a panel link region. A width of the panel link region is referred to as a panel link length (WA). In order to connect the data lines and the gate lines to the TCP 10 like the ribs of a fan as described above, each link line 22 has to be extended by an appropriate extension length (LP). Thus, a panel link region having an appropriate panel link length (WA) is required.
When fabricating a high-resolution LCD device, because of a corresponding increase in the number of gate lines, data lines, TCP output lines, and link lines, the extension lengths of link lines have to be correspondingly increased to maintain the intervals between link lines. Accordingly, the panel link length increases correspondingly in high-resolution applications. Moreover, various lines are formed within the panel link region to supply various control signals or image signals to an active area. Thus, if a panel link length increases, the LCD device correspondingly increases in weight and size of a LCD.